I had Pass X-350 on them before. Cremona is a litte dry on top, so is Pass. I will recommend something more liquid and airy on top, high power tube will be my recommendation.
I am using BAT VK-75SE with Amati, soon will get another pair of Cremona to play with. BAT is slightly under power for my Cremona Auditor in my 18x14 room, but sound is pristine.